--- OA_place: publisher _id: '18766' abstract: - lang: eng text: Poxviruses are large pleomorphic double-stranded DNA viruses that include well known members such as variola virus, the causative agent of smallpox, Mpox virus, as well as Vaccinia virus (VACV), which serves as a vaccination strain for formerly mentioned viruses. VACV is a valuable model for studying large pleomorphic DNA viruses in general and poxviruses specifically, as many features, such as core morphology and structural proteins, are well conserved within this family. Despite decades of research, our understanding of the structural components and proteins that comprise the poxvirus core in mature virions remains limited. Although major core proteins were identified via indirect experimental evidence, the core's complexity, with its large size, structure and number of involved proteins, has hindered efforts to achieve high-resolution insights and to define the roles of the individual proteins. The specific protein composition of the core's individual layers, including the palisade layer and the inner core wall, has remained unclear. In this study, we have merged multiple approaches, including single particle cryo electron microscopy of purified virus cores, cryo-electron tomography and subtomogram averaging of mature virions and molecular modeling to elucidate the structural determinants of the VACV core. Due to the lack of experimentally derived structures, either in situ or reconstituted in vitro, we used Alphafold to predict models of the putative major core protein candidates, A10, 23k, A3, A4, and L4. Our results show that the VACV core is composed of several layers with varying local symmetries, forming more intricate interactions than observed previously. This allowed us to identify several molecular building blocks forming the viral core lattice. In particular, we identified trimers of protein A10 as a major core structure that forms the palisade layer of the viral core. Additionally, we revealed that six petals of a flower shaped core pore within the core wall are composed of A10 trimers. Furthermore, we obtained a cryo-EM density for the inner core wall that could potentially accommodate an A3 dimer. Integrating descriptions of protein interactions from previous studies enabled us to provide a detailed structural model of the poxvirus core wall, and our findings indicate that the interactions within A10 trimers are likely consistent across orthopox- and parapoxviruses. This combined application of cryo-SPA and cryo-ET can help overcome obstacles in studying complex virus structures in the future, including their key assembly proteins, interactions, and the formation into a core lattice. Our work provides important fundamental new insights into poxvirus core architecture, also considering the recent re-emergence of poxviruses. acknowledged_ssus: - _id: EM-Fac - _id: LifeSc - _id: ScienComp acknowledgement: "This work was funded by the Austrian Science Fund (FWF) grant P31445 and ISTA. I\r\nwould like to express my gratitude to the Scientific Service Units, particularly the Lab\r\nSupport Facility, the Scientific Computing Facility and the Electron Microscopy Facility\r\nfor their tremendous support. I want to especially thank Alois for assisting me with the\r\ninstallation of countless new software and for troubleshooting cluster issues. A special\r\nthanks goes to Valentin for his outstanding support in cryo-EM data acquisition and\r\nhis ongoing help in improving the process to ensure that I obtained the best possible\r\ndata from my sample." alternative_title: - ISTA thesis article_processing_charge: No author: - first_name: Julia full_name: Datler, Julia id: 3B12E2E6-F248-11E8-B48F-1D18A9856A87 last_name: Datler orcid: 0000-0002-3616-8580 citation: ama: Datler J. Elucidating the structural determinants of the poxvirus core using multi-modal cryo-EM. 2024. doi:10.15479/at:ista:18766 apa: Datler, J. (2024). Elucidating the structural determinants of the poxvirus core using multi-modal cryo-EM. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:18766 chicago: Datler, Julia. “Elucidating the Structural Determinants of the Poxvirus Core Using Multi-Modal Cryo-EM.” Institute of Science and Technology Austria, 2024. https://doi.org/10.15479/at:ista:18766. ieee: J. Datler, “Elucidating the structural determinants of the poxvirus core using multi-modal cryo-EM,” Institute of Science and Technology Austria, 2024. ista: Datler J. 2024. Elucidating the structural determinants of the poxvirus core using multi-modal cryo-EM. Institute of Science and Technology Austria. mla: Datler, Julia. Elucidating the Structural Determinants of the Poxvirus Core Using Multi-Modal Cryo-EM. Institute of Science and Technology Austria, 2024, doi:10.15479/at:ista:18766. short: J. Datler, Elucidating the Structural Determinants of the Poxvirus Core Using Multi-Modal Cryo-EM, Institute of Science and Technology Austria, 2024. corr_author: '1' date_created: 2025-01-07T10:23:12Z date_published: 2024-12-30T00:00:00Z date_updated: 2026-04-07T12:59:44Z day: '30' ddc: - '570' degree_awarded: PhD department: - _id: GradSch - _id: FlSc doi: 10.15479/at:ista:18766 file: - access_level: closed checksum: 3e51cab327c754045c3d29c1a50cc9a9 content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document creator: jstanger date_created: 2025-01-07T12:15:11Z date_updated: 2025-01-07T12:15:11Z file_id: '18769' file_name: PhD_thesis_Julia_Datler.docx file_size: 38814932 relation: source_file - access_level: open_access checksum: 22fabe5b97950bf852212f6edb555173 content_type: application/pdf creator: jstanger date_created: 2025-01-07T12:15:14Z date_updated: 2025-01-07T12:15:14Z file_id: '18770' file_name: PhD_thesis_Julia_Datler.pdf file_size: 12044865 relation: main_file success: 1 file_date_updated: 2025-01-07T12:15:14Z has_accepted_license: '1' keyword: - cryo-EM - cryo-ET - cryo-SPA - Structural Virology - Poxvirus - Vaccinia Virus - Structural Biology language: - iso: eng license: https://creativecommons.org/licenses/by-nc-nd/4.0/ month: '12' oa: 1 oa_version: Published Version page: '106' project: - _id: 26736D6A-B435-11E9-9278-68D0E5697425 call_identifier: FWF grant_number: P31445 name: Structural conservation and diversity in retroviral capsid publication_identifier: isbn: - 978-3-99078-049-7 issn: - 2663-337X publication_status: published publisher: Institute of Science and Technology Austria related_material: record: - id: '12334' relation: part_of_dissertation status: public - id: '14979' relation: part_of_dissertation status: public status: public supervisor: - first_name: Florian KM full_name: Schur, Florian KM id: 48AD8942-F248-11E8-B48F-1D18A9856A87 last_name: Schur orcid: 0000-0003-4790-8078 title: Elucidating the structural determinants of the poxvirus core using multi-modal cryo-EM tmp: image: /images/cc_by_nc_nd.png legal_code_url: https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode name: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) short: CC BY-NC-ND (4.0) type: dissertation user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd year: '2024' ... --- OA_place: publisher _id: '18101' abstract: - lang: eng text: "The Retroviridae family consists of two sub-families, the Orthoretrovirinae and the\r\nSpumaretrovirinae. The Orthoretroviruses contain important human pathogens, such as the\r\nhuman immunodeficiency virus 1 (HIV-1). They also harbor other retrovirus species which\r\nare regularly used as model systems to study the retroviral life cycle. The main structural\r\ncomponent of the retroviruses, is the Gag protein and its truncation derivatives occurring\r\nduring viral maturation. Orthoretroviral Gag assemblies have been extensively studied to\r\nunderstand the interactions that confer stability and morphology to viral particles.\r\nThe Spumaretrovirinae subfamily represent an early diverging branch of the Retroviridae.\r\nIts members, the Foamy viruses (FV), share most of the conventional features found in\r\nretroviruses. However, they also possess multiple characteristics that make them unique. In\r\nparticular, FV Gag does not get extensively cleaved as in orthoretroviruses. Hence, the Gag\r\narchitecture deviates from the canonical domain arrangement in FV. They also exhibit a\r\npeculiar particle morphology, having no apparent immature state and a seemingly\r\nicosahedral mature particle. Due to this, many fundamental questions on FV structural\r\nassembly mechanisms remain open. To answer these questions, was the main focus of this\r\nthesis.\r\nMainly, it is not known how FV assemble their core in a virus particle and what are the\r\nimportant assembly interaction sites within said core. What is the minimum assembly\r\ncompetent domain of FV Gag? Is there a morphological change in the assembly type of FVGag lattices? If so, what is defining these morphological shifts? Finally, it would be\r\ninteresting to know what is the evolutionary relationship between FV and the rest of the\r\nretrotranscribing elements, from a structural point of view?\r\nTo answer these questions, membrane-enveloped mammalian cell-derived FV virus-like\r\nparticles (VLPs) were produced. Cryo-electron tomography (cryo-ET) analysis suggested\r\nthese FV VLPs do not form a canonical retroviral Gag lattice structure, which is in line with\r\nearlier observations. To further evaluate FV Gag assembly competence and morphology,\r\nthe first bacterial cell-derived in vitro VLP assembly system was designed and optimized.\r\nUsing this system with different truncation variants, the minimum assembly competent\r\ndomain of FV Gag was found to be the putative CA300-477 domain. Varying VLP\r\nmorphologies were also observed and strongly suggested residues upstream of CA300-477\r\nplay a role in morphology determination. Finally, a combined cryo-electron microscopy (cryoEM) and cryo-ET approach was taken to analyze tubular assemblies from the minimal\r\nassembly competent domain. This revealed an unexpectedly unique non-canonical\r\nassembly architecture. Three novel lattice stabilizing interfaces were described which\r\nproved to be as unique as the lattice arrangement. Comparison to a newly published FV CA\r\ncore structure revealed the CA-CA interactions in the atypical assembly do not recapitulate\r\nwhat is described for the FV core lattice. However, the new in vitro VLP assembly system\r\nobtained in this thesis also provides an exciting opportunity to study still unresolved FV\r\nassembly features in a potentially facilitated approach compared to conventional methods.\r\nIn summary, this work provided a deeper understanding of the basic FV Gag assembly unit,\r\nas well as presenting the first FV Gag-derived in vitro VLP assembly system. This system\r\nreveals a novel and unique assembly architecture among retroviral in vitro assemblies." acknowledged_ssus: - _id: EM-Fac - _id: LifeSc - _id: ScienComp alternative_title: - ISTA Thesis article_processing_charge: No author: - first_name: Dario J full_name: Porley, Dario J id: 2FD6EA6C-F248-11E8-B48F-1D18A9856A87 last_name: Porley citation: ama: Porley Esteves D. Structural characterization of spumavirus capsid assemblies. 2024. doi:10.15479/at:ista:18101 apa: Porley Esteves, D. (2024). Structural characterization of spumavirus capsid assemblies. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:18101 chicago: Porley Esteves, Darío. “Structural Characterization of Spumavirus Capsid Assemblies.” Institute of Science and Technology Austria, 2024. https://doi.org/10.15479/at:ista:18101. ieee: D. Porley Esteves, “Structural characterization of spumavirus capsid assemblies,” Institute of Science and Technology Austria, 2024. ista: Porley Esteves D. 2024. Structural characterization of spumavirus capsid assemblies. Institute of Science and Technology Austria. mla: Porley Esteves, Darío. Structural Characterization of Spumavirus Capsid Assemblies. Institute of Science and Technology Austria, 2024, doi:10.15479/at:ista:18101. short: D. Porley Esteves, Structural Characterization of Spumavirus Capsid Assemblies, Institute of Science and Technology Austria, 2024. corr_author: '1' date_created: 2024-09-20T10:21:03Z date_published: 2024-09-26T00:00:00Z date_updated: 2026-04-07T13:21:01Z day: '26' ddc: - '570' degree_awarded: PhD department: - _id: GradSch - _id: FlSc doi: 10.15479/at:ista:18101 ec_funded: 1 file: - access_level: closed checksum: 3b8b0bacfe61112f3852744f3170e468 content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document creator: dporley date_created: 2024-09-26T13:40:33Z date_updated: 2025-03-25T23:30:03Z embargo_to: open_access file_id: '18149' file_name: PhD_thesis_DPorley_final_20240919.docx file_size: 14213128 relation: source_file - access_level: open_access checksum: 6c3a652a8eede874118e11d66a63652f content_type: application/pdf creator: dporley date_created: 2024-09-26T13:41:39Z date_updated: 2025-03-25T23:30:03Z embargo: 2025-03-25 file_id: '18150' file_name: PhD_thesis_DPorley_final_20240926_pdfa1.pdf file_size: 18583031 relation: main_file file_date_updated: 2025-03-25T23:30:03Z has_accepted_license: '1' language: - iso: eng month: '09' oa: 1 oa_version: Published Version page: '131' project: - _id: 2564DBCA-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '665385' name: International IST Doctoral Program - _id: 9B9C98E0-BA93-11EA-9121-9846C619BF3A grant_number: '25762' name: Structural characterization of spumavirus capsid assemblies to understand conserved Ortervirales assembly mechanisms publication_identifier: isbn: - 978-3-99078-041-1 issn: - 2663-337X publication_status: published publisher: Institute of Science and Technology Austria status: public supervisor: - first_name: Florian KM full_name: Schur, Florian KM id: 48AD8942-F248-11E8-B48F-1D18A9856A87 last_name: Schur orcid: 0000-0003-4790-8078 title: Structural characterization of spumavirus capsid assemblies type: dissertation user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd year: '2024' ... --- OA_place: publisher _id: '12491' abstract: - lang: eng text: "The extracellular matrix (ECM) is a hydrated and complex three-dimensional network consisting of proteins, polysaccharides, and water. It provides structural scaffolding for the cells embedded within it and is essential in regulating numerous physiological processes, including cell migration and proliferation, wound healing, and stem cell fate. \r\nDespite extensive study, detailed structural knowledge of ECM components in physiologically relevant conditions is still rudimentary. This is due to methodological limitations in specimen preparation protocols which are incompatible with keeping large samples, such as the ECM, in their native state for subsequent imaging. Conventional electron microscopy (EM) techniques rely on fixation, dehydration, contrasting, and sectioning. This results in the alteration of a highly hydrated environment and the potential introduction of artifacts. Other structural biology techniques, such as nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, allow high-resolution analysis of protein structures but only work on homogenous and purified samples, hence lacking contextual information. Currently, no approach exists for the ultrastructural and structural study of extracellular components under native conditions in a physiological, 3D environment. \r\nIn this thesis, I have developed a workflow that allows for the ultrastructural analysis of the ECM in near-native conditions at molecular resolution. The developments I introduced include implementing a novel specimen preparation workflow for cell-derived matrices (CDMs) to render them compatible with ion-beam milling and subsequent high-resolution cryo-electron tomography (ET). \r\nTo this end, I have established protocols to generate CDMs grown over several weeks on EM grids that are compatible with downstream cryo-EM sample preparation and imaging techniques. Characterization of these ECMs confirmed that they contain essential ECM components such as collagen I, collagen VI, and fibronectin I in high abundance and hence represent a bona fide biologically-relevant sample. I successfully optimized vitrification of these specimens by testing various vitrification techniques and cryoprotectants. \r\nIn order to obtain high-resolution molecular insights into the ultrastructure and organization of CDMs, I established cryo-focused ion beam scanning electron microscopy (FIBSEM) on these challenging and complex specimens. I explored different approaches for the creation of thin cryo-lamellae by FIB milling and succeeded in optimizing the cryo-lift-out technique, resulting in high-quality lamellae of approximately 200 nm thickness. \r\nHigh-resolution Cryo-ET of these lamellae revealed for the first time the architecture of native CDM in the context of matrix-secreting cells. This allowed for the in situ visualization of fibrillar matrix proteins such as collagen, laying the foundation for future structural and ultrastructural characterization of these proteins in their near-native environment. \r\nIn summary, in this thesis, I present a novel workflow that combines state-of-the-art cryo-EM specimen preparation and imaging technologies to permit characterization of the ECM, an important tissue component in higher organisms. This innovative and highly versatile workflow will enable addressing far-reaching questions on ECM architecture, composition, and reciprocal ECM-cell interactions." acknowledged_ssus: - _id: EM-Fac - _id: LifeSc - _id: Bio alternative_title: - ISTA Thesis article_processing_charge: No author: - first_name: Bettina full_name: Zens, Bettina id: 45FD126C-F248-11E8-B48F-1D18A9856A87 last_name: Zens orcid: 0000-0002-9561-1239 citation: ama: Zens B. Ultrastructural characterization of natively preserved extracellular matrix by cryo-electron tomography. 2023. doi:10.15479/at:ista:12491 apa: Zens, B. (2023). Ultrastructural characterization of natively preserved extracellular matrix by cryo-electron tomography. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:12491 chicago: Zens, Bettina. “Ultrastructural Characterization of Natively Preserved Extracellular Matrix by Cryo-Electron Tomography.” Institute of Science and Technology Austria, 2023. https://doi.org/10.15479/at:ista:12491. ieee: B. Zens, “Ultrastructural characterization of natively preserved extracellular matrix by cryo-electron tomography,” Institute of Science and Technology Austria, 2023. ista: Zens B. 2023. Ultrastructural characterization of natively preserved extracellular matrix by cryo-electron tomography. Institute of Science and Technology Austria. mla: Zens, Bettina. Ultrastructural Characterization of Natively Preserved Extracellular Matrix by Cryo-Electron Tomography. Institute of Science and Technology Austria, 2023, doi:10.15479/at:ista:12491. short: B. Zens, Ultrastructural Characterization of Natively Preserved Extracellular Matrix by Cryo-Electron Tomography, Institute of Science and Technology Austria, 2023. corr_author: '1' date_created: 2023-02-02T14:50:20Z date_published: 2023-02-02T00:00:00Z date_updated: 2026-04-07T13:49:23Z day: '02' ddc: - '570' degree_awarded: PhD department: - _id: GradSch - _id: FlSc doi: 10.15479/at:ista:12491 file: - access_level: open_access checksum: 069d87f025e0799bf9e3c375664264f2 content_type: application/pdf creator: bzens date_created: 2023-02-07T13:07:38Z date_updated: 2024-02-08T23:30:04Z embargo: 2024-02-07 file_id: '12527' file_name: PhDThesis_BettinaZens_2023_final.pdf file_size: 23082464 relation: main_file - access_level: closed checksum: 8c66ed203495d6e078ed1002a866520c content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document creator: bzens date_created: 2023-02-07T13:09:05Z date_updated: 2024-02-08T23:30:04Z embargo_to: open_access file_id: '12528' file_name: PhDThesis_BettinaZens_2023_final.docx file_size: 106169509 relation: source_file file_date_updated: 2024-02-08T23:30:04Z has_accepted_license: '1' keyword: - cryo-EM - cryo-ET - FIB milling - method development - FIBSEM - extracellular matrix - ECM - cell-derived matrices - CDMs - cell culture - high pressure freezing - HPF - structural biology - tomography - collagen language: - iso: eng month: '02' oa: 1 oa_version: Published Version page: '187' project: - _id: eba3b5f6-77a9-11ec-83b8-cf0905748aa3 name: Integrated visual proteomics of reciprocal cell-extracellular matrix interactions - _id: 059B463C-7A3F-11EA-A408-12923DDC885E name: "NÃ\x96-Fonds Preis für die Jungforscherin des Jahres am IST Austria" publication_identifier: isbn: - 978-3-99078-027-5 issn: - 2663-337X publication_status: published publisher: Institute of Science and Technology Austria related_material: record: - id: '8586' relation: part_of_dissertation status: public status: public supervisor: - first_name: Florian KM full_name: Schur, Florian KM id: 48AD8942-F248-11E8-B48F-1D18A9856A87 last_name: Schur orcid: 0000-0003-4790-8078 title: Ultrastructural characterization of natively preserved extracellular matrix by cryo-electron tomography type: dissertation user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd year: '2023' ...